Anastigmatic medium-power microscope objective providing a flattened image field

ABSTRACT

The invention provides an anastigmatic medium-power microscope objective which provides a flattened image field and which consists of a small number of lenses divided into two groups for correcting substantially all image errors. The first group of lenses comprises a thick meniscus lens having positive refractive effect next to the object, and one or two converging lens members arranged close to each other, at least one of the latter being a doublet having a convex cemented surface facing the object. The second group of lenses consists of a simple converging lens and a simple diverging lens following the lenses of the first group along the optical axis from the object. The spacing of the two groups of lenses is appropriately designed for the desired purpose of providing an anastigmatic flattened image with these groups of lenses and is at least half the axial distance between the object and the apex.

United Slat [72] Inventor Walter Klein Wlssmar. Kreis Wetzlar, Germany [2]] Appl. No. 377,912 [22] Filed June 25, I964 [45] Patented July i3, 197! I73] Assignee Ernst Leltz G.n|.b.li.

Wetzlar, Germany [32] Priority July 9. i963 [33] Germany [3| 1 L 45292 IXl/42h [54] ANASTIGMATIC MEDIUM-POWER MICROSCOPE OBJECTIVE PROVIDING A FLAT'I'ENED IMAGE FIELD 5 Claims, 3 Drawing Figs. [52] U.S. Cl 350/216, 350/220 (5 I Int. Cl... G02b 9/34, G02b 9/60, G02b 2 H02 [50] Field ol Search 350/2 i6. 220, I76, I77, 224

[56] Relerences Cited UNITED STATES PATENTS 2,206,I55 7/1940 Boegehold 350/216 Primary ExaminerJohn K. Corbin Attorney-Erich M. H. Radde ABSTRACT: The invention provides an anastigmatic medium-power microscope objective which provides a flattened image field and which consists of a small number of lenses divided into two groups for correcting substantially all image errors. The first group of lenses comprises a thick meniscus lens having positive refractive effect next to the object, and one or two converging lens members arranged close to each other, at least one of the latter being a doublet having a convex cemented surface facing the object. The second group of lenses consists of a simple converging lens and a simple diverging lens following the lenses of the first group along the optical axis from the object. The spacing of the two groups of lenses is appropriately designed for the desired purpose of providing an anastigmatic flattened image with these groups of lenses and is at least half the axial distance between the object and the apex.

ATENTHI J','l 1 3 mm INVENTOR ER KL E/N m u..u.wa4,

3 ,5 92 ,5 30 1 2 ANASTIGMATIC MEDIUM-POWER MICROSCOPE and the indices of refraction m. n n m. and n, for the e line A of the spectrum and the dlSPCI'SiVC indices Y Y, Y3, Y4, and Y, or successive ones of said lenses. starting from the object,

. are as follows: The present invention relates to a microscope ob ective providing a flattened image field, and more particularly to a 5 TABLE Uh medium-power objective of this type wherein a small number of objective lenses corrects all image errors to a sufficient m l.70 degree. Various constructions of microscope objectives have been '0 I n 40' proposed to flatten the image field. However, conventional 3; anastigmatic microscope objectives are either quite expensive,

i.e. they comprise lens members which are difficult to produce and/or which are large in number, or at least some of the image errors are badly corrected.

It is the primary object of the present invention to make an The constructional data for a fully corrected example of the IS type shown in FIG. I are given in the following table:

anastigmatic microscope objective of medium power at TABLE In moderate cost.

This and other objects are accomplished by making the ob- Rad ,fifi lfifigg n jective of two groups of lenses. The axial distance between the two groups oflenses is at least half the axial distance between 10-0w; 52491 68.3 the object and the apex of the objective lens facing the image "-4 16 projected by the objective. The first group of lenses next to the mm 0 object consists of a negative meniscus lens of considerable MM axial thickness next to the object to constitute the front lens of -a i the objective and one or two converging lens members ar- +9.84 ranged close to each other, at least one converging lens 11,-2.0 1.0mm 59.2 member being a doublet having a convex cemented surface 11-3025 facing the object. The axial distance of the converging lens n-+29.232 I members from each preceding lens is smaller than the axial an thickness of such lens member. The second lens group consists 1,-1.0

of a simple converging lens and a simple diverging lens followdwu .3430 28.1 ing the converging lens, starting from the object. n=+10.938

The great distance between the two groups of lenses permits a very good correction of all image field errors without impair- I w 20 ing the quality of the objective along the optical axis. 22 1 The accompanying drawing and the following tables show 8-38 preferred embodiments of this invention; 1

d :152: zz ggzfizs; with a Single cememed In the table, B'e is the magnification of the microscope, f, is

the focal length of the entire optical system, A is the aperture,

FIG. 2 showing a simple converging lens and a Cement d up is the Seidel coefficient for the Petzval curvature of the doublet lens member in the first group, and Petzval surface, and 2r is the Seidel coefficient for the astig- FIG. 3 being an embodiment with two cemented doublet mamm' lens members in he first group In an ob ective with a magnification of about 25 l and an In the drawing he specification. and in: claims to aperture of about 0.5. it is preferred to use two converging designates the distance from the last objective lens to the conf mFmbcrs m the first group In one ofwch an jugate image plane. ob ective, as shown in FIG. 2, the respective focal lengths f',,

In the embodiment of FIG. 1, the objective has a focal f and the respective axial distanc, between h length [and the respective focal lenghs fhfbfa'fb and he 5 ect and the first lens. and between successive ones ofsaid lenrespective axial distances between the object and the first lens, 565 bcmg as follows:

In this embodiment, the successive radii of curvature r r,, '3. n. r.. r-,, r,, r,. r and r and the successive axial 3 4 and the indices of refraction n,, n,, :1 n n, and n. for the e TABLE VIIIa line of the spectrum and the dispersive indices Y Y,, Y,, Y.. dl 1 Y and Y, of successive ones of said lenses, starting from the 0.4! da+di i.3[ object, are as follows: 8% g: 5 0.1] d1 20] 0.3a; -n i.0[ TABLE Vb a; -r: 13;

6/ |rs| 1t l.50.. 40 1.5] (H 6-0 m 1.60.. 40 0.7 n 20 fl3 l.65.. 46 8] (I'll m l.65.. 40 [0 1.2] 17 6] m i.50.. 40 1.5; -n 3] 1i| l.60.- n 4fi "I 2.51 7 6] 1.8] i'n (4f The constructural data for this embodiment of the type shown in Figure 2 are given in the following table:

and the indices of refraction n., n,, 01,, n n It and n, for the TABLE VI e-line of the spectrum and the dispersive indices Y,, Y,, Y,, Y Y,, Y.., and Y, of successive ones of said lenses, starting from Axial distances 20 the object are as follows: Radil and thicknesses n. v.

TABLE VIIIb d0=0. 17 1. 62491 68. 3 i=0.504 m 1.so 45 r =3.03 m 1.66-. 46 di=6.0 1.67126 66.8 flt .65-. 45 n=-6.0li 1N L65-- 45 l =0.3 m l.65.. 45 r =43.29 m i.60.. 45 (is-1.65 1.67125 56.8 fl1 l.66.. 50 n=7. 877

h=0. 2 m88 a o 0 1 70192 25 o 55 h The constructural data for this embodiment of the type 2 5736 shown in Figure 3 are given in the following table: f1=-l0.56 .7.

d =i.5 1.57450 57.3 TABLE 1x n= m +17 6 h=0. 3 1d m= Asia istaness d l. 2 1.67764 32.0 Radll and thicknesses II. n Tn=+1l 32 ls=15i.7

70-8-3 12 1. 62491 58. 3 gu -24.84 4O 2 45 f 99 tit-3.66 l. 723 29. 8 A==0.60 -4.922 zP=+0. 018 11-044 Er=+0.0i4. ra -51.111

+18 703 di -0.8 1.79192 25.6 m iii-2.12 1.52010 66.0 r =--s. wherein B e Is the total magnificatiomf, IS the focal length of i|=i.s the objective, A is the aperture, and 2p and If are indices tit-0.0 1.70102 25.5 used in Seidel s equations where 292 and ZFlG. are the same =+7.02A as defined above for table Ill. m 57m A further increase in the magnification and of the aperture I l =30.35 requires two cemented doublets in the first group oflenses acdlal 6 1 72311 29 3 cording to the present invention. For a magnification of 40 -m and an aperture of 0.65. for instance, an objective is shown in =+m 769 FIG. 3. The respective focal lengths f,,f,.f,,f,, andf, and the d1= Lz 1.62985 88.8 respective axial distances between the object and the first lens, m=+ti.47 F 6 0 and between successive ones of said lenses 1. 1 1,, 1,, and I are as follows: W: 39.67 I: 4.53 60 50 g' i TABLE vn "2+ 1,6! 1, 30] 2.0) 11 4.0[ 4.0! i0.0[ 8.0] fl -0I wherein fi'e is the total magnification, f, is the focal length of 10.0! -ft 20.0 l 0! 5 the ob ective, A is the aperture, and 2p and II are when 0 li 0-7/ used in Seidels equations where 2p and El are the same as 0 1: l.0[ I defined above for table Ill. 0 1. l-6f I claim:

ln this embodiment, the successive radii of curvature r r,,' r,. n. 13.1.. n, r,, r,, r m. and n, and the successive axial thicknesses, d,, d,. d,, d d,,, d and d of said lenses. starting from the object, are as follows:

1. In an improved anastigmatic medium-power flat field 7g microscope objective having a first and a second group of lenses positioned along an optical axis. the first group of lenses being positioned nearest to the object plane and consisting of a thick negative meniscus converging lens constituting the front lens of the object and a converging doublet having a convex cemented surface facing the object. and the second group of lenses being positioned farthest from the object plane consisting of a simple converging lens and a simple diverging lens positioned the farthest away from the object, the axial distance between the lenses of the first group and the axial thickness of the front lens of the objective being such that the axial distance of the converging doublet from the front lens is smaller than the axial thickness of the front lens, and the axial distance between the first and second group of lenses being at least hall the axial distance between the object and the apex of the objective lens facing the image projected by the objective, and wherein the parameters of the lenses are as follows:

wherein p: is the total magnification, f, the objective, A is the aperture, and 2p used in Seidel's equations.

2. In an improved anastigmatic medium-power flat field microscope objective having a first and a second group of lenses positioned along an optical axis, the first group of lenses being positioned nearest to the object plane and consisting of a thick negative meniscus, converging lens constituting the front lens of the objective and two cemented converging doublets at least one having a convex cemented surface facing the object, and the second group of lenses being positioned farthest from the object plane consisting of a simple converging lens and a simple diverging lens positioned farthest away from the object, the axial distance between the lenses of the first group being such that the axial distance of the converging doublets from each preceding lens is smaller than the axial thickness of the preceding lens, and the axial distance between the first and second group of lenses being at least half the axial distance between the object and the apex of the objective lens facing the image projected by the objective.

3. The microscope objective of claim 2, wherein the parameters of the lenses are as follows. wherein B: is the total magnification, f, is the focal length of the objective, A is the aperture, and 2p and 21 are indices used in Seidel's equations.

4. In an improved anastigmatic medium-power flat field microscope objective having a first and a second group of lenses positioned along an optical axis, the first group of lenses being positioned nearest to the object plane and consisting of a thick negative meniscus, converging lens constituting the front lens of the objective, a converging doublet having a convex cemented surface facing the object and a simple converging lens positioned between the front lens and the doublet, and

is the focal length of and 21 are indices Axial dlstances Radll and thicknesses n. r,

do= 0.17 1. 52491 58. 3 lo=0.312 V1= -2.45

ds=2-l2 1. 52010 05. 0 T 5.181

I: 1.5 n= on ds=1.5 1.72311 29.3 7 9 to I -0.3 r +16.759 d l 38 5: 30.67 Is =4.53 A =0.65 2P =+0.054 Z1 =+0.011

the second group of lenses being positioned farthest from the object plane consisting of a simple converging lens and a simple diverging lens positioned farthest away from the object, the axial distance between the lenses of the first group being such that the axial distance of the converging lenses from each preceding lens is smaller than the axial thickness of the preceding lens, and the axial distance between the first and second group of lenses being at least half the axial distance between the object and the apex of the objective lens facing the image projected by the objective.

5. The microscope objective of claim 4, wherein the parameters of the lenses are as follows:

Axial distances Itadll and thicknesses n. I.

tip-0.17 1. 52491 58. 3 10 0.594 7| -3.03

dt==2.2 1. 57086 63. 0 r 10.55

ls=30.3 r|-+23.392

d;- 1.5 1. 57485 57. 8 a a l7 6 [4-0.3 m=='r 32 tit-1.2 1. 67764 32. 0 r" a f. -5.99 A-0.50 ZP-+0.0l8 lib-+0.0.

is the focal length of and 2p and 21 are indices UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 592, 530 Dated July 13 1971 Inventor-(s) Walter Klein It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 42, crP" should read 2P-. Column 3, line 48, P" should read !',P--. Column 4, line 65 p should be P- and line 66, "2, should be 2.P. Column 5, line 39, should be EP-, line 59, the period should be a colon between lines 59 and 60 the following table should be inserted:

Axial distances Radii and thicknesses n '5} e FORM P040150 USCOMM-DC eons-pas A U 5 GOVERNMENT PRINTING OFFICE} 1969 O-JGE-JM UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 530 Dated July 13 1971 Inventor(s) W ]t K1Q-in It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

- Page 2 r 40. 328 (1 l. 5 1. 72311 29 3 r O0 1 0 3 r 16. 759 G 1.2 1. 62985 38. 8 r 11. 47 1 152. 0

fi 4.53 Zr 0.011

and line 61, "if" should be -P-.

Column 6, delete lines 1 through 29, inclusive; line 69, "if" should be ZP--.

Signed and sealed this 20th day of June 1972.

(siJAL) fittest EDL'JABD T LFLEI'CPIMLJR. ROBERT GOTISCHALK Attesting Officer Commissioner of Patents U S GOVEWNMENY PRINTINCI OFFICE I959 O356-33 

1. In an improved anastigmatic medium-power flat field microscope objective having a first and a second group of lenses positioned along an optical axis, the first group of lenses being positioned nearest to the object plane and consisting of a thick negative meniscus converging lens constituting the front lens of the object and a converging doublet having a convex cemented surface facing the object, and the second group of lenses being positioned farthest from the object plane consisting of a simple converging lens and a simple diverging lens positioned the farthest away from the object, the axial distance between the lenses of the first group and the axial thickness of the front lens of the objective being such that the axial distance of the converging doublet from the front lens is smaller than the axial thickness of the front lens, and the axial distance between the first and second group of lenses being at least half the axial distance between the object and the apex of the objective lens facing the image projected by the objective, and wherein the parameters of the lenses are as follows:
 2. In an improved anastigmatic medium-power flat field microscope objective having a first and a second group of lenses positioned along an optical axis, the first group of lenses being positioned nearest to the object plane and consisting of a thick negative meniscus, converging lens constituting the front lens of the objective and two cemented converging doublets at least one having a convex cemented surface facing the object, and the second group of lenses being positioned farthest from the object plane consisting of a simple converging lens and a simple diverging lens positioned farthest away from the object, the axial distance between the lenses of the first group being such that the axial distance of the converging doublets from each preceding lens is smaller than the axial thickness of the preceding lens, and the axial distance between the first and second group of lenses being at least half the axial distance between the object and the apex of the objective lens facing the image projected by the objective.
 3. The microscope objective of claim 2, wherein the parameters of the lenses are as follows:
 4. In an improved anastigmatic medium-power flat field microscope objective having a first and a second group of lensEs positioned along an optical axis, the first group of lenses being positioned nearest to the object plane and consisting of a thick negative meniscus, converging lens constituting the front lens of the objective, a converging doublet having a convex cemented surface facing the object and a simple converging lens positioned between the front lens and the doublet, and the second group of lenses being positioned farthest from the object plane consisting of a simple converging lens and a simple diverging lens positioned farthest away from the object, the axial distance between the lenses of the first group being such that the axial distance of the converging lenses from each preceding lens is smaller than the axial thickness of the preceding lens, and the axial distance between the first and second group of lenses being at least half the axial distance between the object and the apex of the objective lens facing the image projected by the objective.
 5. The microscope objective of claim 4, wherein the parameters of the lenses are as follows: 